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| After 20 years, another 10 to 15 percent of thermal windows will fail as they are exposed to the elements. And by the 25 year mark a growing number of cladding systems will have major thermal failures, requiring the building skin and/or its mechanical systems to be upgraded entirely. |
What are the real costs facing owners of glass condos? (By Lloyd Alter) - There is much to complain about glass condos; we have noted that they are costly to heat and cool, often uncomfortable and hard on the furniture. As John Straube has noted, "Glass and aluminium are great for cookware but not for buildings." What we haven't noted is the inevitable cost of replacement. In Canadian Facility Management and Design magazine, one of those dead tree trade publications I get sent as an architect, quantity surveyor Joe Pendlebury describes the problem of the glass wall. He claims that five percent of thermal windows may have failed even before they are delivered to the job site.
After 20 years, another 10 to 15 percent of thermal windows will fail as they are exposed to the elements. And by the 25 year mark a growing number of cladding systems will have major thermal failures, requiring the building skin and/or its mechanical systems to be upgraded entirely.
And he is talking about commercial buildings here, not just the window wall systems used on condos. Thanks to the different rates of expansion between aluminium and glass, over the years the seals break down between the framing and the glass, the argon gets out of the sealed units and moisture gets in. Pretty soon the whole system has to be replaced.
The costs of replacing entire walls of glass are prohibitive to some owners of high-rise structures. The average cost to remove and replace a cladding system from a swing stage is about $200 per square foot. As the typical floor-area-to-cladding ratio in high-rise structures is .33, this will translate into a cost of $66 per square foot over the above grade areas of a typical building.
And that doesn't include the cost of the interior finishes, where drywall might have to be busted to expose the anchoring systems, ceilings, and possible relocation of occupants while the work is being done. The owner of a 700 Square foot unit might get hit with an assessment of close to $50,000 if there isn't a big reserve fund to cover it.
Fortunately the building codes are changing and the all glass buildings are no longer the standard. However there are a whole lot of them out there now that are going to have to be fixed in the rapidly approaching future, and it is going to cost serious money.
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| Glass and aluminium have very different coefficients of expansion, and the sealants are exposed to sun, wind and rain for years. |
Why Architects Shouldn't Build Condos out of Glass And People Shouldn't Buy Them: Glass balcony panels are raining down on the streets of Toronto from the shiny new condominiums, building envelope expert John Straube was interviewed on Ontario Morning to discuss the problem. He didn't say a whole lot about why the panels are falling, but did a great explanation of the problems that come from building condos out of glass. There is a big difference between the glass on office buildings and on condos; the former is usually curtain wall, that runs continuously on the exterior, the latter is window wall, really a modified store-front wall redesigned for condos, supported by each floor and running from slab to slab. It is a lot cheaper.
- Glass and aluminium are great for cookware but not for buildings.
- With floor to ceiling glass, you have nowhere to hang a picture, place your furniture or change your underwear.
- Energy efficiency is five times lower than a conventional wood framed house.
- The glass area is so large that it is difficult to control temperature, it's too hot or too cold.
- If we care about the long term, we should go for a balance, no more than 30 or 40 percent glass.
Straube noted that while aluminium and glass are easy to clean and durable, the sealants and gaskets are not, and will need maintenance and replacement down the road. This is not cheap or easy, and the burden falls on the condominium association and the owners. (Glass and aluminium have very different coefficients of expansion, and the sealants are exposed to sun, wind and rain for years.)
Straube suggests that the reason architects choose to build like this is about style and not cost, but I disagree, having worked with the architect and window manufacturer for the project with the falling glass (which was from the balconies, not the windows, and from a different manufacturer) on some of the earliest all-glass projects in Toronto in the 90s. It's a lot cheaper and a lot easier for a developer to work with one trade, the window wall supplier, than to coordinate among trades when mixing precast or brick with glass.
The building code encourages it too, by regulating the R-value of wall constructions, like saying all solid walls have to have an R-Value of R20, but not regulating the overall heat loss through a wall, so a builder can put up a glass tower with an R Value of R4 and comply with the code.
If the authorities in Ontario said, for example, that a total wall area must have an average R-value of 10, then designers would have to figure out a mix of solid wall and glass, and if they wanted more glass they would need to buy better windows, and stop building radiator fin balconies.
But that would raise costs and prices and might kill the golden goose that is the Canadian condo boom, so they will just let the condo purchasers worry about it a decade from now.
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| Prof. Kesik, projecting 10 years into the future when he estimates their glass walls will fail prematurely. |
Glass Towers May Be Sexy, But They Need To Put A Coat On: Ted Kesik doesn't mince words. When everybody else was gaga over Jeanne Gang's Aqua he described it: Take your clothes off, attach a series of highly conductive fins, like the kind they put on motorcycle engines, to the skeleton of your body, and go stand outside in January... Then tell the person who is dressed for winter they are boring, overly practical people who are squashing creative expression.
Now he is back with more architectural pornography imagery, discussing Toronto's new condos and their very thin glass walls with Dave LeBlanc of the Globe and Mail: As a building scientist, I look at buildings the way a doctor looks at a body: I say ‘Ah, it may look sexy but boy, that’s not very healthy. I don’t know if I’d want to be that thin.”
When he is not complaining about new glass buildings, he is helping to fix older ones as part of Toronto's Tower Renewal Project. The towers built in the sixties are solid and had real walls with punched windows, so that they can be retrofitted by adding an exterior insulation and finish system. He calls the old buildings "tough, rugged and robust".
The same cannot be said for our new glass towers. Dave LeBlanc quotes Kesik in the Globe And Mail - “That’s not what’s going to happen to all those wonderful buildings down at Concord Place,” snarls Prof. Kesik, projecting 10 years into the future when he estimates their glass walls will fail prematurely. “They’re going to have to evacuate.” So why do young people line up to purchase there despite the fact that energy performance is usually as bad as a 1960s or 70s building before tower renewal? It’s either the media portraying them as “sexy” or, more likely, that buyers just aren’t aware of their failings: “No industry that I know of provides so little factual information to the consumers of its product; you look at every other industry and they have to convey technological advances or they don’t get sales.”
